Screw propeller



- Nov. 23, 1937. E. L. BELLMAN 2,099,922

- SCREW PROPELLER Filed March 4, 1935 EZ-L- Eellm B'n Patented Nov. 23, 1937 SCREW PROPELLER 4 Edward Lawrence Bellman, Rockford, 111., assignor of one-half to Elmer W. Johnson, Rockford, 111.

Application March 4, 1935 Serial No. 9,236

1 Claim.

' to suit varying conditions, such as in taking ofi,

flying, landing, and in accordance with engine speed and atmospheric conditions.

One of the primary objects of my invention is the provision of a propeller, in which the propeller blades will be automatically rotated to effect the desired pitch, without any effort on the part of the pilot, so that the propeller will be operating at a maximum emciency at all times.

Another salient object of my invention is to provide a propeller having blades rotatable on a longitudinal axis, with their centers of gravity forward of the main body of the blades, whereby the air or other fluid will be impinged against the trailing body portions of the blades to vary the pitch thereof according to the force of the fluid pressure against the blades, means being provided for resisting said pressure, and to normally hold the blades in a neutral position for cutting the air, whereby coasting or volplaning will be enhanced without propeller hindrance or drag.

A further object of my invention is to provide a propeller having propeller blades rotatably supported by the hub, with cams on the inner ends of the blades acting against a pressure plate, the pressure plate functioning to normally hold the blades in a position to out the wind when the propeller is at rest, and for acting against the fluid pressure tending to rotate the blades when the propeller is in use.

A further important object of my invention is 1 the provision of novel means for forming the hub and blades, whereby a blade can be quickly removed from or associated with the propeller in case of damage.

5 Afurther object of my invention is the provision of novel means for adjusting the tension of the pressure plate, and to provide manual means for actuating the blades against the tension of said pressure plate.

5 A still further object of my invention is to provide an improved propeller of the above character, which will be durable and efilcient in use, one that will be simple and easy to manufacture, and one which can be placed upon the market at a reasonable cost.

With these and other objects in view, the invention consists in the novel construction, arrangement, and formation of parts, as will be hereinafter more specifically described, claimed, and illustrated in the accompanying drawing, in 6 which drawing 1- Figure 1 is a side elevation of one form of my improved propeller.

Figure 2 is a transverse section through the propeller hub, taken on the line 22 of Figure 1, 10 looking in the direction of the arrows.

Figure 3 is a longitudinal section through the propeller hub, showing the position of the blades under action of fluid pressure.

Figure 4 is a longitudinal section through a slightly modified form of my propeller, the blades being in a state of rest.

Referring ,to the drawing in detail, wherein similar reference characters designate corresponding parts throughout the several views, the 20 letter 1? generally indicates my improved propeller, which includes an axially disposed hub 5 and radially extending blades 6. While in the drawing I have only illustrated two blades, it'is to be understood that any number of blades can 25 be used without departing from the spirit or the scope of the invention.

The hub 5 is of a substantially conical shape, and includes a front section 1 and a removable rear section 8. A cupped flange B, forming an 34. integral portion of the drive or driven shaft 9, is provided for the purpose of forming a closure for the juxtaposed end of the hub. An interior chamber I0 is formed in the hub 5, and this chamber receives the. stems or roots ll of the :n propeller blades 6. The meeting faces of the'sections I and 8 of the hub support suitable bearings l2 for the blade stems or roots, and the extreme inner ends of the stems have formed thereon, or secured thereto, the oppositely directed o cams l3. Slidably mounted within the chamber I0 is a pressure plate II, which is normally urged into engagement with the cams so as to hold the blades in a feathering position to cut the wind when the propeller is in a state of rest. Any 4r desired means can be provided for urging the pressure plate ll toward the cams,. and to resist turning movement of the cams. In the present instance I have illustrated a relatively heavy expansion coil spring I5. The spring is fitted with- 50 inthe chamber l0, and one end of the same bears against one end wall of the chamber, and the other end of the spring bears against the pressure plate.

necessary to remove the section 8 from the section '4'. This will permit instant accessibility to be had into the chamber In. The sections of the hub can be rigidly secured together in any preferred manner, such as by the use of cap bolts l6. As heretofore stated, the blades 6 have roots or stems H formed on their inner ends, which are rotatably mounted in the hub, and the body portions ll of the blades extend rearwardly of the axis of the blades. This is for the purpose of permitting fluid pressure to impinge against the body portions of the blades to effect the rotation of said blades so that the pitch thereof can be changed according to the propeller speed, or the pressure of the fluid acting against the blades.

Normally, the body portions of the blades are at right angles to the direction of revolution, and thus the blades act to efliciently cut through the air during volplaning and the like, so that the propeller will not act as a drag. This feature is also particularly useful in windmills, as

it prevents injury to the propeller in high winds.

When the propeller is used on an airplane, and it is desired to take off, the blades will instantly move to their greatest pitch to bring about the maximum efficiency for climbing. In other-words, the propeller will be turned at a high rate of speed, and the pressure of the air against the body portions of the blades will rotate the blades against the tension of the spring.

The propeller also efficiently acts as a governor, in view of the fact that after the pilot sets the motor for a given speed, the blades of the propeller will act automatically and keep the engine at practically the same speed at all times. If a plane declines downwardly, and the throttle of the motor is set at the desired speed, the.

instant the plane starts the decline, theblades will pitch to a degree, keeping the motor at a constant speed. This is particularly useful in a combat plane, in that the pilot could cut off his motor and leave the blades to cut the wind, and permit the airplane to thus volplane many miles without being heard.

There is never any back pressure against the motor of an airplane, or any speeding up of a motor-from on-rushing air against the propeller. If an airplane was travelling 'at a set speed, and met with a head wind, the blades would pitch at once to prevent motor racing.

If desired, means can be provided for varying the tension of the spring, and means can also be provided for manually adjusting the position of the propeller blades. The manual means for adjusting the propeller blades is particularly useful where the propeller is used on a windmill.

In Figure 4 I have illustrated means for manually adjusting the tension of the spring, and for manually varying the position of the blades. A follower plate 20 can engage the forward end of the spring, and a screw 2| can be provided for engaging the follower plate to shift the position thereof longitudinally of the propeller hub. The head of the screw can be received in a pocket 22 formed in the front of the hub, and the pocket can be normally closed by a removable head 24.

To bring about the manual shifting of the blades, pins 25 can be slidably carried by the propeller hub for engaging against the rear faces of the cams on the blades. These pins can be pushed forwardly for turning the cams and the blades against the tension of the spring. Any desired means can be utilized for operating the pins, and in the present instance I have shown the pins connected with a shift'collar 26, which is slidably mounted on the propeller shaft. A yoke 21 is provided for engaging the shift collar, and by swinging the yoke on its pivot, the shift collar can be moved forwardly to slide the pins. The propeller can be made to operate either left-handed or right-handed, and this is accomplished by merely changing the position of 'the cams l3 on the stems of the propeller blades.

If preferred, a spring can be utilized for engaging the rear faces of the cams, as well as the front faces of the cams, in which instance the propeller would act efficiently in either direction of rotation without changing the position of the cams.

I can provide rigid stops arranged in the path of the cams to limit the movement of the cams under influence of fluid pressure on the blades.

Other changes in details may be made without departing from the spirit or the scope of my invention, but what I claim as new is:

A variable pitch propeller comprising a tapered conical hub having a front pocket and a rear chamber portion, a propeller shaft terminating with a flange for closing the hub chamber,

means for securing said flange to the hub, the

surfaces of said hub and flange being routed to form radial bearings, blade stems journaledin the bearings, cams carried by each stem disposed in the rear chamber portion, said cams being oppositely disposed relative to each other, a pressure plate mounted in said chamber portion engageable with the cams, a follower plate in said chamber portion, an expansion spring disposed between the plates, an adjusting screw extending through the hub pocket into the chamber and engageable with the follower plate, and a head cap in threaded union with the hub pocket serving as a closure therefor.

EDWARD LAWRENCE BELLMAN. 

